1. Field of Invention
The present invention relates to a measurement circuit. More particularly, the present invention relates to a dielectric constant measurement circuit and a dielectric constant measurement method.
2. Description of Related Art
The general dielectric constant measurement system needs using the expensive and heavy network analyzer to measure the offset frequency and the return loss parameter of the oscillator, but the network analyzer cannot be integrated into the general consumer electronics.
In general, integrated circuits are utilized to construct a phase locked loop (PLL) serving as the interface circuit of the sensing system. The interface circuit reads the value of the controlling voltage from the voltage-controlling oscillator, and then the analog-digital converter converts the frequency information into the digital signal. The analog-digital converter will restrict the readout frequency resolution of this system, and it will need an exactly standard reference frequency signal.
The conventional dielectric constant measurement system must be applied with the large instrument to read the oscillation frequency and the quality factor of the oscillator. But analog-to-digital converter embedded in the dielectric constant measurement system will restrict the resolution and consume more power. Therefore, it is one of the important subjects and the objective needs to increase the resolution of readout frequency, to reduce the power consumption and further to integrate the dielectric constant measurement system into the integrated circuit.